Power brake booster right?
The hose is a 3/8" I.D., and you'll need to install a fitting to your new manifold so you will still have power brakes.
This is easiest done with the manifold off the engine, but not impossible to do on the engine if you take precautions not to get aluminum down the ports.
Your local auto supply store should have the fittings in stock and your hardware, the correct thread taps and right size drill bits.